. >> narrator: the obama administration may soon reverse the bush stem cell policy, and scientific breakthroughs may open up whole new approaches less reliant on embryonic stem cells. still, parkinson's remains a race between the disease and the ock. back home in the bay area, i met up again with tom shearer, who i'd first gotten to know at the parkinson's exercise class. it was tom who first said to me that this wasn't a battle he thought he could win. >> reach. look at your knee more. good. there you go. >> narrator: what worries tom and his wife madeleine now isn't so much the struggle to keep moving, but the battle everyone dreads, the one that involves your mind. >> one of the real major problems that i think almost anybody with parkinson's has, which is the memory aspect. i don't know where that's going to lead. >> there was a long period when tom would go out and get lost, and neighbors would call us and say, "come and get him, he's at the corner of such and such." >> i did get lost in downtown oakland, which, if you've lived in the area, you know, you really shouldn't get lost. >> narrat